Harold Cohen was born in 1928 in London. After serving in the RAF, he studied painting at the Slade School of Fine Arts between 1948-52. He then spent six months in Italy upon being awarded the Abbey Travelling Scholarship. His first one-man show was at the Ashmolean Museum in Oxford, in 1951; and his first solo London show was at Gimpel Fils in 1954.

He spent 1959-61 in the United States on a fellowship and whilst out there an exhibition of his work was shown at the Allan Stone Gallery in New York. On his return to London he took a place teaching at the Slade School, 1962.

In 1966 he showed at the British Pavilion, Venice Biennale; at Documenta 3; the Paris Biennale; the Carnegie International, and many other important exhibitions. In 1968 he took up a Visiting Professorship at the University of California at San Diego which resulted in his settling there.

Cohen's research into the basic skills necessary for creating art led to his inventing a computer model capable of autonomously generating an endless succession of different drawings. This programme, which he named AARON, has been seen producing original 'freehand' drawings at the Tate Gallery, the San Francisco Museum of Art, the Stedelijk Museum Amsterdam, and many other international art and science centres. Cohen was formerly Visiting Scholar at the Artificial Intelligence Laboratory at Stanford University, and Director of the Center for Research into Computing and the Arts at USC San Diego. His writing has been published widely and he has attracted considerable media attention.

After a period of research and scientific invention Cohen returned to painting with a mural 100 feet long for a show at the San Francisco Museum of Art in 1979. Since then he has continued to create original works of art based on those produced by Aaron.